The Department of Pediatrics, College of Physicians and Surgeons, Columbia University, New York, N.Y., has participated in the research activities of Children's Cancer Study Group (formerly Children's Cancer Study Group A) since 1957. In the early years, investigations were confined primarily to Phase III cooperative chemotherapeutic trials related to the treatment of acute childhood leukemia. Since 1964 the scope of activities has been broadened to include cooperative randomized trials of treatment of solid tumors of childhood. More recently, added emphasis has been placed on Phase I and Phase II studies of new agents in both acute leukemia and solid tumors, as well as ancillary studies related to the pathogenesis and natural history of these diseases. Beginning in 1969, a comparative trial related to the treatment of Wilms' tumor was started on a national level. Intergroup studies (including Children's Cancer Study Group, Cancer and Acute Leukemia Group B and Southwest Oncology Group) have been mounted, even more recently, related to the treatment of rhabdomyosacrcoma and Ewing's sarcoma. Protocols for the treatment of (1) localized unilateral retinoblastoma, (2) localized bilateral retinoblastoma and (3) extraocular retinoblastoma have been prepared. The first of these was activated for patient entry in June 1977. The protocol for extraocular retinoblastoma was activated in March 1978. The bilateral retinoblastoma protocol is still in preparation. In the past two years, there has been increased emphasis on the multidisciplinary and multimodal nature of the various investigations with more active participation by radiotherapists, radiologists, pathologists, ophthalmologists, urologists and neurologists.